With special greetings for Tomek ;-)
This how stairs should be cleaned, 3 persons, 2 are cleaning with special machine, one person securing whole process, around markings, warnings etc.
Cleaning stairs was our favorite complainint subject – everyday walking to work we had luck with stairs cleaning on our station – cleaner in a mask, with dry sweeper, no water and dost going straight in our faces.
This team is the best example how it should be done.

Mixed company (japanese girl ant the one with camera live here, rest are turists), coming back home from some jam-session, next to me was musical equimpent, mystery hand on right side reaching for cookie…